Coolant Loss

[alno1995]

I have an 04 Sierra 4.8L with 62K. When I bought it it had 57K. Soon after I bought it the check engine light came on. The dealer replaced the Cat. I notice it has a bit of lifter noise and I have to add a quart or so of coolant every 500 miles. Very slow leak. I can detect no leaks. I have extended warranty. Can the dealer do a pressure test to see if the heads or head gaskets are bad? Thanks for any help

[jro909]

i would say yes...you may have castec heads which means by by engine hello new one...take it to the dealer asap, otherwise check the bung hole on the water pump i've dealt with 4.8s that have leaky water pumps and the coolant gets burned off before it hits the ground...

[rogersinsel]

I have an 04 Sierra 4.8L with 62K. When I bought it it had 57K. Soon after I bought it the check engine light came on. The dealer replaced the Cat. I notice it has a bit of lifter noise and I have to add a quart or so of coolant every 500 miles. Very slow leak. I can detect no leaks. I have extended warranty. Can the dealer do a pressure test to see if the heads or head gaskets are bad? Thanks for any help

 

A quart every 500 miles is No slow leak. That would about every week, week and a half for me. you can do the pressure test.

[Nytemare]

A quart of coolant every 500 miles...how long has this been going on....any longer than a couple thousand and you likely have coolant in the oil...Thats a very bad thing.

 

Likely your truck has Castec heads...do a search for it...you will get the TSB about it.